The current application describes the research background, career development plan and Institutional commitment pertinent to the scientific career of the applicant. As required by the K02 mechanism, the applicant has already independent research support (R01 AI087803; NIAID). The aim is to strengthen and enhance the applicant's research efforts by providing at least 75% protected research time and thereby improving opportunities for building a successful science career. The applicant's studies are focusing on a novel domain of gastro-intestinal enzymology related to celiac disease. Celiac disease is an auto-immune disorder in which a host anti-self response is triggered by gluten-derived peptides in genetically predisposed individuals. Symptoms can be mostly reversed upon adherence to a gluten-free diet. Currently this avoidance strategy is the only treatment option available to celiac patients. It requires a life-long commitment to the gluten-free regimen and represents a social as well as a financial burden to the patient. One of the promising new therapeutic avenues pursued for celiac disease is gluten degradation and detoxification with enzyme preparations. We have discovered that the oral microbiome is a novel and rich source of gluten-degrading enzymes. In the past year we have isolated characterized and speciated the gluten enzyme-producing microorganisms. The elucidation of natural resident bacteria degrading gluten in the upper gastro-intestinal tract opens new therapeutic opportunities to neutralize the deleterious effects of these proteins. The major research goals for the next five years are to (1) Determine microbial enzyme activities under mock- gastro/duodenal conditions; (2) To characterize, clone and recombinantly express the most promising enzyme candidates; (3) To assess gliadin detoxification by selected microbes and purified enzyme preparations in vitro in a T-cell proliferation assay and in vivo in a mouse model for celiac disease. In addition, future studies are planned to investigate the striking structural similarities between gliadins and salivary proline-rich proteins (PRPs), and to investigate if PRPs possess gluten-like properties in terms of their capability to enhance/modulate immune responses in diet-responsive and refractory celiac disease. RELEVANCE: Gluten are proteins which are not tolerated by people who suffer from celiac disease. A promising therapeutic approach is the use of enzymes as dietary supplements to achieve gluten degradation and detoxification in vivo. The current application seeks to identify novel gluten-degrading enzymes expressed by resident microbes of the human upper gastrointestinal tract for their exploitation in the treatment of celiac disease.